Peroxides and their Effects on Plants Essays

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Peroxides such as peroxyacetyl nitrate (PAN) and H_2 O_2 are present in polluted air.Of the corresponding ozone concentrations, PAN may yield up to 5% -20% in centers of “photosmog”, for example, the Los Angeles region. The observation of the effects of PAN on plants first occurred in 1945 in the Los Angeles area as a silvery-bronze glazing on leaf crops like spinach (Spinaceaoleraceae) and lettuce (Lactuca sativa). PAN, a constituent of smog, the acidic, eye-irritating haze, fills the air periodically over certain industrial regions and large cities. It is photochemically formed via the action of UV and visible radiation on a complex mixture of 〖NO〗_x , oxygen and volatile unsaturated hydrocarbon generated in exhaust of automobile. …show more content…
Peroxyacetylnitrate reacts with NADPH. It seems that there is no further reaction between PAN and the oxidized compounds such as NAD and nicotinamide adenine dinucleotide phosphate (NADPH). The reaction between peroxyacetyl nitrate and olefins forms epoxides and further products of lipid peroxidation whereas the reactions with primary amines leads to their acetylation.

Figure 5: Typical injury of peroxyacetyl nitrate (PAN).A glazy bronzing on the underside of newly expanded potato leaves.
(Source from: http://www.omafra.gov.on.ca/english/crops/facts/91-015.htm)

Ethene
Ethene (formerly ethylene) is a retarding phytohormone. It acts as an antagonist to the growth stimulators auxins and gibberellins as well as inducing stem thickening, fruit ripening, senescence, increased resistance and general responses to stress and wounding. Under natural conditions, the formation of ethene occurs via S-adenosyl methionine (SAM) and 1-amino-cyclopropane carboxylic acid (ACC), from which it is oxidatively released.Under acute stress situations like mechanical wounding and freezing,the origin of ethene in small amounts may be from the oxidative breakdown of stress situations mega-3 polyunsaturated fatty acids, for example, linolenic acid. Under the catalysis of copper ions, the omega-1 and -2fragment of the fatty acid derive ethene together with ethane.
Chaotic lipid peroxidation produces ethane in the absence of copper ions. Generally, ethene is determined as

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